A spring harrow is an implement featuring a frame that is towed over the ground by an agricultural tractor so that a set of spring tines depending downward from the frame engage the ground surface to break up and smooth out the same. A common type of spring harrow employs a double coil spring tine, where a pair of horizontally spaced apart coils wind around a shared horizontal axis with inner ends of the coils joined together by a central cross-bar running parallel to that axis. A pair of tine shafts depend downwardly from the outer ends of the two coils. The central cross-bar is mounted to the implement frame and the coils independently and respectively bias the two tine shafts downward about the coil axis to keep the lower ends of the tine shafts engaged with the ground. Single coil tines are sometimes also used, where each tine features only a single coil spring and single respective downward tine shaft.
A known problem with spring tines is they may tend to wear relatively quickly, and accordingly require frequent replacement.
U.S. Pat. No. 6,425,446 of Gates addresses this issue by mounting a one-piece hardened edge member to a front side of each tine shaft at the lower end thereof to increase the effective hardness at the leading side of the lower portion of the resulting tine structure. The member is made of chrome to provide greater hardness than the spring tine material, while being suitable for attachment to the spring tine by welding.
While the Gates solution does provide a cutting edge of improved durability relative to the tine itself, there remains room for improvement, as use of more durable materials than chrome, such as tungsten carbide, would further improve the wear life of the tine, but challenges remain in how to attach a tungsten carbide wear piece to the tine, as the tungsten carbide is not suitable for welded attachment to the spring tine.
Applicant has addressed this problem through development of a unique two-piece cutting edge attachment for harrow tines.
Other references relating to attachments for mounting on spring tines include U.S. Pat. Nos. 184,089, 4,834,190, 5,027,907 and 6,138,771, and Japanese Patent Document 11172646, which individually and collectively fail to suggest the solution put forth by the present invention.